Balloon catheter

ABSTRACT

A balloon catheter includes a balloon and an inner shaft. The inner shaft includes a marker member arranged on an outer periphery of a coil body having a sparsely wound portion in which gaps are formed between adjacent windings of the wire of the coil body. A distal end part and a proximal end part of the marker member are arranged at a position facing a void formed within one of the gaps between the adjacent windings of the wire of the coil body. The inner shaft of the balloon catheter therefore will not buckle, preventing damage to the balloon by contact with the marker member when the balloon catheter is passed through the inside of a curved blood vessel.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Application No. 2015-065856filed on Mar. 27, 2015, the content of which is incorporated byreference herein in its entirety.

BACKGROUND

The disclosed embodiments relate to a medical device. Specifically, thedisclosed embodiments relate to a balloon catheter to be inserted into astenosis site inside a blood vessel for expanding the stenosis site.

Balloon catheters to be inserted into a stenosis site inside a bloodvessel for expanding the stenosis site have already been proposed. Aballoon catheter mainly comprises a balloon as an expanding body, anouter shaft joined to a proximal end of the balloon, and an inner shaftinserted within the balloon and the outer shaft. Further, a metal markermember having radiopacity is commonly provided inside the balloon sothat the position of the balloon can be detected under exposure ofirradiation.

For example, Japanese Patent No. 3659664 discloses a catheter forexpanding a blood vessel. The catheter includes a platinum contrastmarker (a marker member) attached to a medical tube (an inner shaft)comprising an inner layer, a coil layer as a reinforcement layer, and anouter layer.

As another example, Japanese Patent No. 3219968 discloses aballoon-expandable catheter having an inner tube (an inner shaft) and aballoon. A radiopaque marker fits in the inside of a depressed groovearranged on an outer periphery of the inner tube in the inside of theballoon. The radiopaque marker is covered by a heat-shrinkable tube.Moreover, also disclosed is a balloon-expandable catheter in which theradiopaque marker is arranged on the outer periphery of an inner tubenot having a depressed groove. Here too, the radiopaque marker iscovered by a heat-shrinkable tube.

However, the catheter for expanding a blood vessel disclosed in JapanesePatent No. 3659664 has the following disadvantages. Since the markermember is attached to the outer periphery of the inner shaft and isexposed to an inner periphery of the balloon, there is a risk that anend portion of the marker member may damage the balloon. Further, adifference in rigidity may arise when a flexible inner shaft and ahighly rigid marker member are used, creating a risk that the innershaft will buckle due to an excessively concentrated stress at theattachment position of the marker member.

Moreover, in the balloon-expandable catheter disclosed in JapanesePatent No. 3219968 above, processing steps such as polishing and etchingare required for providing a depressed groove. Therefore, themanufacturing process will be disadvantageously complicated. Further,disadvantageously, a site where the depressed groove is provided tendsto have decreased strength due to the reduction in cross-sectional area.Furthermore, since the outer diameter of a balloon portion will belarger for a configuration in which the radiopaque marker is arranged onthe outer periphery of the inner tube and is covered by aheat-shrinkable tube, the diameter of the balloon catheter cannot beeasily reduced. Further, disadvantageously, in a case where the markermember is made of a highly rigid metal, the marker member itself cannotbe easily deformed as required to follow the curvature of a blood vesseland the like, and the portion of the balloon catheter at which themarker member is arranged may easily become stuck in the blood vessel.

SUMMARY

Accordingly, an object of the disclosed embodiments is to provide aballoon catheter in which there is no risk of damaging the balloon, andin which a diameter of a portion where the marker member is arranged canbe reduced. Additionally, it is an object of the disclosed embodimentsto prevent the portion of the balloon catheter where the marker memberis arranged from becoming stuck even when inserted into a curved bloodvessel.

A balloon catheter of the disclosed embodiments comprises a balloon andan inner shaft joined to the balloon. The inner shaft comprises an innerlayer, a coil body arranged at an outer periphery of the inner layer andhaving a sparsely wound portion where a wire is sparsely wound, a markermember arranged at an outer periphery of the coil body, and an outerlayer covering the coil body and the marker member. At least a portionof one of a distal end part and a proximal end part of the marker memberis arranged at a position facing a void formed between adjacent windingsof the wire of the sparsely wound portion.

When the above balloon catheter in this configuration is inserted into acurved blood vessel, at least a portion of one of the distal end partand the proximal end part of the marker member can enter into the voidformed between adjacent windings of the wire of the coil body.Therefore, a stress concentration generated at a location where themarker member is arranged can be relieved, preventing the inner shaftfrom buckling. Further, the end portions (the distal end part and theproximal end part) of the marker member can be prevented from projectingtoward the inner periphery of the balloon. Moreover, the manufacturingprocess is simplified because the marker member is covered by the outerlayer without requiring the use of another member. Furthermore, there isno risk that the marker member will damage the balloon. In addition,because the outer layer covering the coil body also serves to cover themarker member, an outer diameter of the inner shaft can be kept small.

Further, at least one of the distal end part and the proximal end partof the marker member is preferably curved toward the inner shaft. Inthis configuration, at least one of the distal end part and the proximalend part forms a smooth and continuous tapered shape. Therefore, rupture(burst or breakage) of the balloon due to contact with the marker membercan be prevented. Further, even in a case where external force isapplied to the marker member when the balloon catheter curves, an edgeof the marker member can enter into the void and make contact with thewire of the coil body, allowing the movement of the marker member to becontrolled.

In the balloon catheter of the disclosed embodiments, there is no riskof damaging the balloon of the balloon catheter, and the diameter of theportion where the marker member is arranged can be reduced.Additionally, the portion of the balloon catheter where the markermember is arranged will not get stuck in the blood vessel even when theblood vessel is curved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a partial cross-sectional top view of a balloon catheteraccording to the disclosed embodiments.

FIG. 2 shows a partial enlarged cross-sectional view of the ballooncatheter of FIG. 1.

FIG. 3 shows a partial enlarged cross-sectional view illustrating astate of the balloon catheter of FIG. 1 when curved.

FIGS. 4A and 4B show partial enlarged cross-sectional views of a ballooncatheter according to the disclosed embodiments.

FIG. 5 shows a partial enlarged cross-sectional view of a ballooncatheter according to the disclosed embodiments.

FIGS. 6A and 6B show diagrams illustrating a marker member of a ballooncatheter according to of the disclosed embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

Below, balloon catheters according to the disclosed embodiments will bedescribed in detail. However, the present invention shall not be limitedto those embodiments, and modifications in design can appropriately bemade. Note that in FIGS. 1 to 5, the left side corresponds to the distalend, which is to be inserted into the body, and the right sidecorresponds to the proximal end, which is to be operated by an operatorsuch as a physician. Further, for easier understanding, smaller parts(such as a marker member 70 arranged inside a balloon 20) are shown in asomewhat exaggerated manner relative to the dimensions of other members.The same reference numbers are assigned in the figures for parts thatare in common.

A balloon catheter 10 of the disclosed embodiments can be used fortreating a stenosis site inside a blood vessel of the heart and thelike. The balloon catheter 10 comprises a balloon 20, an outer shaft 30,a connector 40, an inner shaft 50, and a tip 60, as shown in FIG. 1.

The balloon 20 serves to expand the stenosis site, and comprises amember made of a resin. In addition, a distal end of the balloon 20includes a distal end attachment part 22, and a proximal end of theballoon 20 includes a proximal end attachment part 23. The distal endattachment part 22 is joined to a distal end of the inner shaft 50through the tip 60, and the proximal end attachment part 23 is joined toa distal end of the outer shaft 30.

The outer shaft 30 serves to feed a fluid to the balloon 20, andcomprises a tubular member which constitutes an inflation lumen 36 forfeeding the fluid. Further, the outer shaft 30 has a distal end outershaft portion 31, a guide wire port portion 33, a middle outer shaftportion 35, and a proximal end outer shaft portion 37 in that order fromthe distal end of the outer shaft 30. Note that the guide wire portportion 33 corresponds to a portion in which the distal end outer shaftportion 31, the middle outer shaft portion 35, and the inner shaft 50are joined.

The inner shaft 50 is inserted into the distal end outer shaft portion31, and the inflation lumen 36 is formed between the distal end outershaft portion 31 and the inner shaft 50. Moreover, the proximal endouter shaft portion 37 comprises a metal tubular member referred to as aso-called hypotube. In addition, a distal end of the proximal end outershaft portion 37 is inserted into and joined to a proximal end of themiddle outer shaft portion 35. Further, the connector 40 is attached toa proximal end of the proximal end outer shaft portion 37. Accordingly,when a liquid for expanding the balloon 20 such as a contrast agent orphysiological saline is fed from an indeflator (not shown) attached tothe connector 40, the liquid flows into the balloon 20 through theinflation lumen 36, allowing the balloon 20 to expand.

Note that the distal end outer shaft portion 31 and the middle outershaft portion 35 are preferably formed of a tube comprising a resin suchas polyamide, polyamide elastomer, polyolefin, polyester, or polyesterelastomer. Further, the proximal end outer shaft portion 37 ispreferably configured with a superelastic alloy such as stainless steel(SUS304) or a Ni—Ti alloy.

Moreover, a core wire 90 is attached to an inner periphery of the distalend of the proximal end outer shaft portion 37. The core wire 90 has acircular cross-section, and is formed of a tapered metal wire with adiameter that decreases toward its distal end. In addition, the corewire 90 passes through the middle outer shaft portion 35 and the guidewire port portion 33, and extends into the distal end outer shaftportion 31. Further, the core wire 90 has a pressing member 92positioned near and proximal to a proximal end of the guide wire portportion 33. Due to the positioning of the pressing member 92, when apushing force and a rotating force are applied to the core wire 90, thepressing member 92 makes contact with the guide wire port portion 33,allowing the pushing force and the rotating force to be transmitted tothe distal end outer shaft portion 31 and the inner shaft 50.Alternatively, the core wire 90 may directly make contact with the guidewire port portion 33 instead of contacting the guide wire port portion33 with the pressing member 92. In this manner, when a pushing force anda rotating force are applied to the core wire 90, the pushing force andthe rotating force can be transmitted to the distal end outer shaftportion 31 and the inner shaft 50. Note that the core wire 90 ispreferably formed of a superelastic alloy such as stainless steel(SUS304) or an Ni—Ti alloy.

Further, a proximal end guide wire port 55 is formed at a proximal endof the inner shaft 50 by being joined to the guide wire port portion 33of the outer shaft 30. Furthermore, a distal end guide wire port 69 isformed at the tip 60 arranged at the distal end of the inner shaft 50.

Moreover, as shown in FIG. 2, the inner shaft 50 has a tubular innerlayer 51 in the inside thereof, the tubular inner layer 51 forming aguide wire lumen 511 for inserting a guide wire (not shown).

Moreover, a coil body 52 covering the inner layer 51 is arranged at anouter periphery of the inner layer 51. The coil body 52 has a sparselywound portion 522 where a wire 521 with a rectangular cross-section issparsely wound so that gaps are formed between adjacent windings of thewire 521.

Moreover, two marker members 70 with a cylindrical shape are arranged ateach of a distal side and a proximal side of an outer periphery of thesparsely wound portion 522 of the coil body 52 in the inside of theballoon 20. Furthermore, an outer layer 53 covers the coil body 52 andthe marker member 70.

Note that the inner layer 51 and the outer layer 53 are preferablyformed of a resin such as polyethylene, polyurethane, polyamide,polyamide elastomer, polyolefin, polyester or polyester elastomer. Notethat the coil body 52 is preferably formed of a superelastic alloy suchas stainless steel (SUS304) or a Ni—Ti alloy. Moreover, the markermember 70 is preferably formed of a radiopaque metal material such asplatinum or tungsten.

Further, the gaps between the adjacent windings of the wire 521 arefilled with the outer layer 53 at a region between the adjacent windingsof the wire 521 of the coil body 52 where the marker member 70 is notarranged. In contrast, in a region where the marker member 70 isarranged, a void 54 is formed between the adjacent windings of the wire521 (that is, the adjacent windings of the wire 521 are not filled withthe outer layer 53 in this region). In the balloon catheter 10, a distalend part 701 and a proximal end part 702 of the marker member 70 areeach arranged at a position facing an unfilled gap, and thus the void 54is formed at each of the distal end part 701 and the proximal end part702 of the marker member.

In the balloon catheter 10 having the above configuration, when theballoon catheter 10 is inserted into a curved blood vessel, the innershaft 50 curves along with the blood vessel as shown in FIG. 3. At thistime, at least a portion of the distal end part 701 and a portion of theproximal end part 702 of the marker member 70 can enter into thecorresponding void 54 of the coil body 52 on the side of the curvedinner shaft 50 that faces into the curve. Therefore, a stressconcentration generated at a position where the marker member 70 isarranged can be relieved, preventing the inner shaft 50 from buckling.Further, the projection of the distal end part 701 and the proximal endpart 702 of the marker member 70 toward the side of the inner peripheryof the balloon 20 can also be controlled. Furthermore, the marker member70 can be covered by the outer layer 53 without using another member.Therefore, the manufacturing process is simplified, and there is no riskof damaging the inner periphery of the balloon 20. Moreover, the outerlayer 53 also serves to cover the marker member 70 and the coil body 52.Therefore, the outer diameter of the inner shaft 50 inside the balloon20, as well as the diameter of the entire inner shaft 50, can be keptsmall.

In the balloon catheter 10, the void 54 is formed at each of the distalend part 701 and the proximal end part 702 of the marker member 70.However, buckling of the inner shaft 50 can be prevented even in thecase of the configurations shown in FIGS. 4A and 4B. In theseconfigurations, the void 54 is formed at only one of the distal end part701 and the proximal end part 702 of the marker member 70.

Specifically, only the proximal end part 702 of the marker member 70 isarranged at a position facing the void 54 in the configuration shown inFIG. 4A. In this case, the gaps between adjacent windings of the wire521 facing the distal end part 701 of the marker member 70 are filledwith the outer layer 53. In the configuration shown in FIG, 4B, only thedistal end part 701 of the marker member 70 is arranged at a positionfacing the void part 54. In this case, the gaps between the adjacentwindings of the wire 521 facing the proximal end part 702 of the markermember 70 are filled with the outer layer 53.

The balloon catheter 10 may include a marker member 71 in which a distalend part 711 and a proximal end part 712 each project toward the void 54by curving inside (toward the void 54). In this configuration, thedistal end part 711 and the proximal end part 712 form a smooth andcontinuous tapered shape. Therefore, a risk of damaging the innerperiphery of the balloon 20 with the end portions (the distal end part711 or the proximal end part 712) of the marker member 71 can beeliminated, preventing rupture (burst or breakage) of the balloon 20 dueto contact with the marker member 71. Further, even in a case where theballoon catheter 10 curves and external force is therefore applied tothe marker member 71, the end portions of the marker member 71 that haveentered into the void 54 can make contact with the wire 521 of the coilbody 52 to control the movement of the marker member 71. The endportions that have entered the void 54 may be curved such that the endportions reside completely inside the void.

In the configuration shown in FIG. 5, both the distal end part 711 andthe proximal end part 712 of the marker member 71 are curved toward theinner layer 51. However, the marker member 71 may be formed so that onlyone of the distal end part 711 and the proximal end part 712 is curvedtoward the inner layer 51,

The balloon catheter 10 may include a marker member 72 formed by curvinga parallelogram metal plate A, shown in plan view in FIG. 6A. In thiscase, as shown in FIG. 6B, a distal end part 721 and a proximal end part722 of the marker member 72 are almost entirely arranged at a positionfacing the void 54. The distal end part 721 and the proximal end part722 of the marker member 72 may be curved toward the inner layer 51.

In the balloon catheter 10, the number of the marker members 70 to 72 tobe provided inside the balloon 20 may be one or more. Moreover, thecross-sectional shape of the wire 521 of the coil body 52 is not limitedto a rectangular cross-section, but may be of other shapes such as acircular cross-section.

What is claimed is:
 1. A balloon catheter comprising: a balloon; and an inner shaft joined to the balloon, the inner shaft comprising: an inner layer; a coil body arranged on an outer periphery of the inner layer and having a sparsely wound portion in which gaps are formed between adjacent windings of a wire forming the coil body; a marker member arranged on an outer periphery of the coil body at the sparsely wound portion and having a distal end part and a proximal end part, and an outer layer covering the coil body and the marker member, wherein at least one of a distal end part and a proximal end part of the marker member is arranged at a position facing a void formed within one of the gaps between the adjacent windings of the wire of the coil body.
 2. The balloon catheter according to claim 1, wherein the gaps between the adjacent wires of the coil body are filled with the outer layer in a region where the marker member is not arranged.
 3. The balloon catheter according to claim 1, wherein the distal end part and the proximal end part of the marker member are each arranged at a position facing a void formed within one of the gaps between the adjacent windings of the wire of the coil body.
 4. The balloon catheter according to claim 2, wherein the distal end part and the proximal end part of the marker member are each arranged at a position facing a void formed within one of the gaps between the adjacent windings of the wire of the coil body.
 5. The balloon catheter according to claim 1, wherein in a region where the marker member is arranged, the gaps between the adjacent windings of the wire of the coil body are not filled with the outer layer.
 6. The balloon catheter according to claim 2, wherein in a region where the marker member is arranged, the gaps between the adjacent windings of the wire of the coil body are not filled with the outer layer.
 7. The balloon catheter according to claim 1, wherein the at least one of the distal end part and the proximal end part of the marker member is curved toward the inner layer.
 8. The balloon catheter according to claim 1, wherein both the distal end part and the proximal end part of the marker member are curved toward the inner layer.
 9. The balloon catheter according to claim 7, wherein the at least one of the distal end part and the proximal end part of the marker member resides completely inside the void.
 10. The balloon catheter according to claim 8, wherein both the distal end part and the proximal end part of the marker member reside completely inside the void.
 11. The balloon catheter according to claim 1, further comprising: an outer shaft, wherein: a distal end of the outer shaft is attached to a proximal end of the balloon, the inner shaft extends through the outer shaft and the balloon, and a distal end of the inner shaft is attached to a distal end of the balloon. 